High-speed disconnector using semiconductor technology

Details High-speed disconnector using semiconductor technology High-speed disconnector using semiconductor technology

1999-03-19

2001-05-08

Fleming, Fritz (Department: 2836)

Electrical transmission or interconnection systems

Plural supply circuits or sources

Substitute or emergency source

C307S085000, C307S126000

Reexamination Certificate

active

06229228

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to the field of power electronics. It is based on a high-speed disconnector using semiconductor technology, in accordance with the preamble to the first claim, particularly suitable for uninterruptible power supplies for a load supplied by an AC power supply system. A disconnector of this generic type is described in the French Patent Application FR 2 666 941 A1, for example.
2. Discussion of Background
Disconnectors of this generic type are used for decoupling the load from a supplying AC power supply system. They can be used, in particular, for uninterruptible power supplies. Uninterruptible power supplies have an auxiliary voltage source which can be coupled to the load by coupling means after the load has been disconnected from the AC power supply system. The auxiliary voltage source can, by way of example, comprise a battery, whose DC voltage is converted to an AC voltage by means of a converter, a diesel unit or a rotating system which utilizes the kinetic energy of a generator.
High-speed uninterruptible power supplies having reaction times in the millisecond range are generally used, in particular, for sensitive loads such as computer systems or electronic apparatuses in hospitals. This makes it possible to ensure that all types of transient disruptions and brief voltage dips can be bridged, so that the load always has access to an uninterrupted AC voltage. The power requirement of such loads does not normally exceed a few tens of kW. Devices having power transistors or IGBTs can therefore be used as disconnectors.
Nowadays, solutions using rotary converters are preferred for sensitive loads with a relatively high power requirement (e.g. 0.5-2 MW). In this case, the kinetic energy of a generator is used to support ms-duration dips. If the disruption lasts for a longer time, a further inertial mass is connected by means of a dynamic coupling. In addition, a diesel unit can be started up and connected, in order to cover minute-long disruptions as well. Such rotating systems have been prior art for years and have proved themselves in principle. However, on account of the complex mechanisms and the occasional need for continuous operation of the equipment, they require a high level of maintenance and have significant losses. Furthermore, a number of systems need to be connected in parallel for powers greater than 2 MW.
For economic and technical reasons, it has not been possible up to now to transfer known electronic circuits to high-power applications.
SUMMARY OF THE INVENTION
Accordingly, one object of the invention is to provide a novel high-speed disconnector which uses semiconductor technology, is suitable for very high powers, works reliably and with a minimum of maintenance, and can disconnect a load from the supplying AC power supply system in a matter of milliseconds. This object is achieved by the features of the independent claims.
The essence of the invention, therefore, is that the disconnector comprises a transformer whose primary is connected in series with the AC power supply system and which has a turn-off thyristor connected to its secondary, with an uncontrolled rectifier circuit connected in between. The turn-off thyristor is preferably hard-driven.
The auxiliary AC voltage preferably comprises a DC voltage source which is converted into an AC voltage by means of a converter. The power supply according to the invention is of particularly advantageous design in that the converter is likewise equipped with hard-driven turn-off thyristors.
Further advantageous embodiments can be found in the appropriate dependent claims.
The advantages of the invention can be seen, in particular, in that the electronic disconnector is also suitable for very high powers. It is sufficiently fast to cover brief voltage dips and transients. In addition, the use of hard-driven turn-off thyristors allows a reduction in circuit complexity.


REFERENCES:
patent: 3414872 (1968-12-01), Barron
patent: 5164872 (1992-11-01), Howell
patent: 5210685 (1993-05-01), Rosa
patent: 5347166 (1994-09-01), Schauder
patent: 2 666 941 (1992-03-01), None
General Electric, SCR Manual Second Edition, p. 38, Jan. 1961.*
Abstract—FR 2666941 A.

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